TREATING DIFFICULT FEED GASES TO LNG PLANTS

摘要

Growing demand for Liquefied Natural Gas (LNG) is leading to increased feed production from more difficult gas reservoirs. These reservoirs may contain higher levels of acid components (sulphur components and carbon dioxide). New production may also end up in more difficult to develop environments, like the arctic, offshore or near shore, etc. Conventional upstream processing in such locations is either infeasible or excessively expensive, so more and more production is by full well stream transfer, thereby reducing the upstream facilities to the bare minimum. The consequences are that the LNG facilities are becoming more complex in design and operation.rnThis paper describes how contaminants (e.g. hydrogen sulphide, mercaptans, carbon dioxide, water, salts, organic acids) and the necessary additives (e.g. corrosion inhibitor, hydrate inhibitor) can be dealt with in the integrated designs whilst complying with ever more stringent environmental requirements (e.g. water disposal quality, sulphur dioxide emissions, hydrocarbon losses). It also describes how the various contaminants and additives can interact (e.g. forming emulsions, solids) and can cause additional problems such as foaming, fouling or corrosion. This is illustrated in specific examples.rnThe paper concludes that a functioning and cost-effective line-up can only be achieved with good input data and by using an integrated approach, in which all the processing steps such as pipelining, separation, stabilisation, treating and NGL extraction are considered together.